How to measure a collection’s “quality”?

Dragonfly specimens in the holdings of the Triplehorn Insect Collection.

The Triplehorn Insect Collection is mostly known for beetles and leafhoppers, but we also hold many large and important collections of other groups of insects, like dragonflies.

This post was inspired by a talk given at the 2018 meeting of the Entomological Collections Network in Vancouver by Max Barclay, Senior Curator in Charge of Coleoptera (beetles) at The Natural History Museum in London. Max’s presentation was entitled: “Comprehensiveness as a measure of collections quality,” and his central thesis was that the importance of a collection is a function of three attributes: accessibility, comprehensiveness, and type-richness. To quote from the abstract of his talk, “…a central goal of curation should be to strive to raise comprehensiveness.” I can’t disagree that these are variables that legitimately could go into a calculation of collection quality, but I will push back, hard, on the idea that these three are the only ones to be considered.

I believe that a critical dimension has been left out of this formula: uniqueness. What is it that my collection or your collection has that sets it apart from all the other collections in the world? Why should my bosses – the ones who provide the money that keeps our operation alive – invest in my collection. If there’s nothing unique about it, that is, if everything about it is duplicated somewhere else, then perhaps the thousands of dollars that are invested in the collection each year would be better spent elsewhere. In fact, if there’s nothing different about my collection, why should it exist at all?

Student curating a collection of butterflies

The Parshall collection added both breadth and depth to the Triplehorn Insect Collection butterfly holdings. Dave Parshall collected extensively in Ohio, the upper Midwest, and the Arctic.

Uniqueness is itself a concept with multiple dimensions. Perhaps in my collection we have specimens of species that are found in no other collections anywhere in the world. Perhaps we have more specimens of one particular group than anyone else; specimens collected from a part of the world where no one else has collected; specimens of a species that can no longer be collected either because of legal restrictions or the fact that the species has gone extinct; specimens collected at times of the year that are unique; specimens with associated biological or behavioral details…. I think that this list could go on for quite a while.

Over the past ten years the collections community has seen a dramatic expansion in its portfolio to include electronic recording of specimen data and open access distribution of these data. For the insect collections this has involved a fundamental shift in our approach to specimens. Rare was the collection in which individual insect specimens were formally accessioned: there were just too darn many of them! Sometimes a group of specimens would be accessioned as a single unit, but even then it was rare that even the number of specimens involved was recorded. This is quite at odds with the standard operating procedures in collections of plants, mammals, or fossils. (And anthropological collection curators probably did a spit take when they heard about how insect collections were run!)

Common Claybank Tiger Beetle, Cicindella limbalis, from Colorado.

Due to its history, the Triplehorn collection holds a wealth of beetles from the west and southwest USA.

Today things are changing. We may not formally accession every specimen – with the associated legal concepts – but it has now become normal to give each specimen a unique identifier and to record its metadata in a database. Data aggregators, organizations that bring together data from hundreds of individual collections, provide single points of access to the millions of specimens that have now been digitized. Two of the most prominent of these are the Global Biodiversity Information Facility (headquartered in Copenhagen, and, in the United States, iDigBio ( One lesson has been learned during this exercise: very often even the smallest, most local of collections provides valuable data that are not replicated elsewhere. It may be filling in the gap in the known geographic distribution of a species, extending that distribution beyond what had been known, extending the time of year in which adults are on the wing, or documenting actual range extensions or contractions over time that have been driven (probably) by climate change.

One of the justifications for considering comprehensiveness as a goal of a collection is the idea that there, in one place, one can see and study the true diversity of a group. That may make some aspects of research a little easier: the curators or resident scientists can simply open a cabinet and find all known species of a genus, or an outside researcher could know that if she wants to have a chance to see all those species, she need only visit the museum with that famous complete collection. However, I’d also argue that that is no longer the way biodiversity science is done, at least not in the insect world. For the most part research papers are not based on the holdings of a single collection (or a small number of them). Rather, the investigator tries to reach out to all collections that are known or suspected to have material relevant to the study. This is a corollary to the idea that each collection has something to offer when it comes to understanding the breadth and depth of the world’s diversity.

To attack a straw man, the XYZ Museum of Natural History may have a specimen of every species of butterfly in the world. If each of those species is represented by only one specimen, though, from one place, collected at one point in time, then the collection might be  “comprehensive,” this is hardly an adequate measure of its quality.


About the Author: Dr. Norman Johnson is Professor of Biology and Entomology at The Ohio State University with appointments in EEOB and Entomology. He’s also the Director of the Triplehorn Insect Collection. Norman works with minute, but crucially important, parasitoid wasps. You can learn more about his work by visiting the website of the Johnson Lab.

Leave a Reply

Your email address will not be published. Required fields are marked *